If you are using Ecency App on your phone the icon for Waves is the wavy lines at the bottom. On the website you can find Waves under the Decks tab. Use the blue pencil to write a Wave.
It is for short content... A couple of sentences, a photo, just stop by and say good morning or tell us what is happening right now.
It's a good way to make friends, be engaged with others and possibly even receive a vote or two!